Monoclonal antibodies (mAbs) are one of the most important agents in the pharmaceutical industry. mAbs typically are produced using cultured cells, with mammalian cells often being used to ensure desired folding and glycosylation. Over the last decade, advances have been made in cell culture technology, including the improvement of production media and feeding strategies. These advances have resulted in high cell culture titers. The expressed antibodies, however, generally need to be separated from the host cells and the other components (impurities) in the expression medium in order to be used for their intended purposes.
Because mAbs are generally produced by fermentation, they are accompanied by large amounts of process-related impurities such as host cell protein (HCP), host cell DNA, and media components. Mammalian cells, for example, are sensitive to breakage due to shear stress, and this can result in the release of impurities, such as proteases (i.e., an HCP), which can affect product stability and/or purity. HCP in particular is an important contaminant because it can provoke an immune response at the low parts per million level. Depending on the fermentation conditions, product-related impurities, such as degraded, truncated, and aggregated mAbs, may also be found in the cell culture supernatant. The efficient recovery and purification of antibodies from cell culture media is thus an important part of the antibody purification process, especially in pharmaceutical applications.
Current mAb purification processes generally contain chromatographic polishing steps that target the reduction/removal of product-related and process-related impurities, such as HCP and DNA, high-molecular weight (MW) aggregates, low-MW degradation products, and leachables. Purification processes can be broken down into a series of unit operations, although the operations (and steps therein) can occur simultaneously or sequentially. A common Protein A-based antibody purification process, which covers a broad range of antibodies and conditions, comprises the following unit operations: Protein A capture low→pH virus inactivation→ion exchange chromatography (IEX) polishing (typically two ion exchange chromatography followed by anion exchange chromatography)→virus filtration→and a final ultrafiltration-diafiltration (UF/DF). Further details of antibody purification techniques can be found in Process Scale Purification of Antibodies, Edited by Uwe Gottschalk, John Wiley & Sons, Inc. 2009. The final UF/DF step is considered to complete the purification and to place the antibody into a composition suitable for end-use applications, such as bulk fill and finish, lyophilization for pharmaceutical applications, in vivo testing, clinical use, etc.
Accordingly, it would be desirable to provide an alternative purification process for purifying an antibody composition.